Thunder Jet

[D-1]

To any thunder jet users, at what point will a thunder jet stop flowing? I've seen carbs with 2 or even 3 thunder jets installed and I've always wondered why?? Until the other day tuning a bike and we installed a 120 thunder jet, but still needed more. So we found a Keihn jet with the right threads from a jap/euro bike. It was way bigger by eye ball, so put it in but it didn't fatten up the top end at all. Made me think that there might be a point that the air flow wont pull anymore fuel up the thunderjet hose, hence the 2 and 3 thunderjets I've seen in pictures. Anyone know much about them??

[turboprop]

To any thunder jet users, at what point will a thunder jet stop flowing? I've seen carbs with 2 or even 3 thunder jets installed and I've always wondered why?? Until the other day tuning a bike and we installed a 120 thunder jet, but still needed more. So we found a Keihn jet with the right threads from a jap/euro bike. It was way bigger by eye ball, so put it in but it didn't fatten up the top end at all. Made me think that there might be a point that the air flow wont pull anymore fuel up the thunderjet hose, hence the 2 and 3 thunderjets I've seen in pictures. Anyone know much about them??

the reason for one or more thunder jets is not to increase the flow, but to flatten the fuel curve. The bandwidth expected of a single jet is just too wide. The carbs you see with multiple T-Jets probably had considerable time on the dyno getting the air bleeds for them sized properly for them to come in when they need to.

How this all works is the main jet, and all the T-jets are cumulative, when adding a t-jet, the size of the main jet is reduced. Adding more T-jets gets more complicated, not for the do it yourself crowd. The other thing with adding t-jets is they reduce the flow through the ventury of the carb.

A big carb, like a bored Super G without any t-jets will flow more than enough fuel for a large engine at high RPM. The problem is it will be too rich at lower RPMs. The T-Jets remedy this.

[D-1]

That exactly what Imm trying to fix, the super rich down low. It has worked, the roll on is good with the smaller main jet, and its top is still OK with 1 thunderjet, but i need to add more above 4000rpm but the thunderjet seems to have maxed out. Is this where a second thunderjet may be needed?

What are the air bleeds for the thunderjet you mentioned? Are you talking about the jet in the body?

[turboprop]

That exactly what Imm trying to fix, the super rich down low. It has worked, the roll on is good with the smaller main jet, and its top is still OK with 1 thunderjet, but i need to add more above 4000rpm but the thunderjet seems to have maxed out. Is this where a second thunderjet may be needed?

What are the air bleeds for the thunderjet you mentioned? Are you talking about the jet in the body?

The air bleeds for the tunderjets are in the base of the T-jet. There is a collar with a hole, that hole is the air bleed. The larger the hole the latter the bleed will come in. Also, the closer the jet is located to the venturi, the stronger the signal will be. Some experienced tuners will stager multiple t-jets for this very reason. When the t-jet comes in is a combination of the size of its air bleed and where it is located in relation to the venturi. You might need a few collars to experiment with. Unfortunately, there is no do over when drilling the carb body.